Combination API - CDK, Projen, Typescript

remix of Sam Williams' - Sam Williams's - Conquer Serverless with 7 Practical Projects

Original project uses Serverless Framework v3,

Background

Having recently worked through Sam's course producing the Serverless Framework project here - https://github.com/alanionita/aws-sls-combination-api

Now that SLS is no longer open-source I decided to challenge myself and learn CDK + projen: - CDK for AWS IaC rules - Projen for templating

Description

Architecture:

• API Gateway - HTTP API
• Lambda

Features:

• Fetches a JSON list of latest Steam game discounts
  • Ordered by game rating
• Calculates discounts in GBP with real-time currency conversion

Tech stories:

• API Gateway

  • GET /gameDeals
  • Supports query params
  • ?currency eg. ?currency=gbp

• Lambda

  • Calls 2 other api
  • Error handling
  • Response combining into a valid response
  • Type definitions

Differences from original

• Projen scaffold
  • Does not contain Github Actions workflows
• CDK config for AWS infrastructure-as-code
• Serverless Framework requires lambdas to be stored in src/functions/*
  • Here changed to src/lambdas/* simply because it makes it easier to map AWS services to code
• Serverless Framework automatically names services as service-stage
  • Here implemented with StackProps.stage
• Serverless Framework would produce a deployment / stage, taking a list of stages
  • Here each stage is a new Stack instance and has to be manually defined

  // src/main.ts
  new CombinationApi(cdkApp, 'aws-cdk-combination-api', {
      env: devEnv,
      stage: 'dev' // Or 'prod', 'beta'
  })

Future plans:

• Implement compressed responses from Lambda
  • Currently around 5kb without any compression
  • Serverless Framework has built-in support for this via minimumCompressionSize set to 1024 (1mb)

Usage

Pre-requisites

OS-level installs

• aws-cli (AWS tooling)
  • Install it on local machine
  • Create an account using IAM in the AWS Console
  • Configure the aws cli with aws configure and the above account
    • Project will use default local account, but can be given other accounts via --profile $CUSTOM flag
• volta (Node tooling)
  • Install in on local machine
  • Install Node v20
• Postman
  • For API testing

Configuration

• CDK bootstrap
  • run cdk bootstrap aws://$ACCOUNT_NO/$REGION --verbose to bootstap CDK

Developing

• Clone repo
  • Update names in .projenrc.ts
• Install node packages npm i
• Synthesize the project with projen synth
• Build project with projen build
• Test project with projen test
• Deploy (after green outputs from above)
  • projen deploy
  • Deployment will output the apiEndpoint or URL
• Destroy
  • project destroy

Using the api

• Open Postman
• GET request to API_ENDPOINT/gameDeals?currency=gbp

Output sample:

[
    {
        "title": "Ghostwire Tokyo",
        "storeID": "25",
        "steamRatingPercent": "83",
        "salePrice": 0,
        "normalPrice": 46.32305696841051,
        "savingsPercent": "100.000000",
        "releaseDate": "Fri Mar 25 2022"
    },
    {
        "title": "Need for Speed Unbound",
        "storeID": "8",
        "steamRatingPercent": "61",
        "salePrice": 7.559638735134836,
        "normalPrice": 54.04485342922239,
        "savingsPercent": "86.012287",
        "releaseDate": "Fri Dec 02 2022"
    },
    ...
]

Authors

• Alan Ionita
• Sam Williams - handler and lib

Credits

• Sam Williams - Lambda handler and Serverless Framework setup
• Projen - for awscdk-app-ts template

License

Apache 2.0